The invention relates to a method for transmitting data bits between at least one subscriber station and a radio access arrangement in a radio communication system. The invention also relates to a transmit device for transmitting data bits to a receiver in a radio communication system and a receive device for processing data bits.
In radio communication systems information (for example voice, image information, video information, SMS (Short Message Service) and other data) is transmitted with the aid of electromagnetic waves via a radio interface between the transmitting and receiving stations. The electromagnetic waves are thereby emitted at carrier frequencies that are within the frequency band provided for the respective system. A radio communication system hereby comprises subscriber stations, e.g. mobile stations, radio access arrangements, such as base stations or node Bs, and in some instances further network-side arrangements.
Access by stations to the common radio resources of the transmission medium, e.g. time, space, frequency and power, in radio communication systems is controlled by multiple access MA methods.
Some third generation radio communication systems use a Code Division Multiple Access CDMA method. One such example is WCDMA (Wideband CDMA) systems. These include the FDD (Frequency Division Duplex) components of the UMTS (Universal Mobile Telecommunications System) standard in Europe and the US cdma2000.
With CDMA methods the information to be transmitted is coded using a spreading code, which is made up of a series of so-called chips. Despreading in the receiver takes place by multiplication by the spreading code. If the spreading codes of different subscriber stations are orthogonal, in the case of synchronous data transmission the signals from other subscriber stations can be completely suppressed by despreading.
With direct-sequence CDMA methods, such as IS-95, cdma2000 and WCDMA, the bits to be transmitted are multiplied by a spreading code and then transmitted as a sequence of chips one after the other. In Chen, H. H., Yeh, J. F., Suehiro, N: “A multicarrier CDMA architecture based on orthogonal complete complementary codes for new generations of wideband wireless communications”, IEEE Communications magazine, vol. 39, October 2001, pages 126-134, the use of actual one-dimensional complete complementary spreading codes is proposed for data transmission. It is then possible to start to transmit a data bit before all the chips of the preceding data bit have been sent.